The present invention relates to improvements in grates for use in industrial furnaces or the like, and more particularly to improvements in grate bars which can be utilized in such grates. Still more particularly, the invention relates to improvements in grates of the type wherein the grate bars form rows or tiers of partly overlapping grate bars and at least some of the grate bars are movable longitudinally of the neighboring grate bars. Such grates are disclosed, for example, in U.S. Pat. Nos. 4,235,172, 4,240,402, 4,239,029 and 4,096,809 to which reference may be had, if necessary.
It is already known to utilize in a grate of the above outlined character elongated grate bars whose lateral surfaces are adjacent to or contact each other and which have marginal zones adjacent to the respective lateral surfaces and located outwardly of the downwardly extending ribs which are provided at the undersides of the fuel- and cinder-carrying top sections of the grate bars.
When the mobile grate bars of the grate perform a stirring action, relatively hard or very hard particles (especially particles of metal) are likely to penetrate into the clearances between the lateral surfaces of neighboring grate bars. Such particles are likely to jam and thereby increase the width of clearances between the respective grate bars with a host of undesirable consequences. Thus, the clearances of increased width allow larger quantities of so-called lower wind to penetrate from the underside of the grate into the layer of fuel on the grate to cause uneven combustion and uneven heating of the grate. This entails uneven cooling of the grate bars, especially of those grate bars which are hollow in order to establish paths for forced circulation of a cooling medium. Overheating of grate bars shortens their useful life and causes more pronounced wear. Still, further, a piece of metallic material, cinder or the like which has penetrated between the lateral surfaces of two neighboring grate bars is likely to prevent such grate bars from moving relative to each other which affects the quality of the heating operation and can result in serious damage to grate bars as well as to the equipment which imparts motion thereto.